U.S. Pat. No. 3,084,678 discloses an internal combustion engine of the type described above having opposed pistons and reciprocating sleeves to alter the porting characteristics of the engine. The disclosure of the '678 patent is incorporated herein in its entirety by this reference. The engine of the '678 patent comprises opposed pistons having reciprocating sleeves around each piston, wherein related pistons and sleeves are connected to the same crankshaft. This resulted in a configuration that does not permit for adjustment of the timing of the sleeves with respect to the pistons to maximize efficiency and power. Thus, once an engine is constructed pursuant to the '678 patent, the timing of the movement of the reciprocating sleeves is fixed with respect to the movement of the related pistons.
U.S. Pat. No. 7,234,423 discloses an improved internal combustion engine of the type described above now having reciprocating sleeves connected to a shaft separate and distinct from the crankshaft. The disclosure of the '423 patent is also incorporated herein in its entirety by this reference. The engine of the '423 patent could advance or retard the timing of the motion of the reciprocating sleeve shaft with respect to the motion of the piston crankshaft through the additional shaft. However, the '423 patent did not teach how to advance or retard the timing without the use of an additional shaft. Furthermore, it was still not possible in the '423 to increase or decrease the amount of overlap between the intake/exhaust ports and the ported slots in the reciprocating sleeve shaft.
Accordingly, there is a need for a similar engine design that allows the timing between the pistons and the piston sleeves to be adjusted without the use of a secondary shaft. Furthermore, there is a need for a similar engine design that allows for the amount of overlap to be controlled between the intake/exhaust ports and the ported slots in the reciprocating sleeve shaft. The present invention fulfills these needs and provides other related advantages.